Answer: collapse. Explanation: A pair of bright moons is the word "moon", that is, "friend" falls at the foot of the mountain, which means the word "friend" is below the word "mountain". It is "collapse".

First, the explanation of the collapse.

1 crashed.

2. rupture.

3. Being hit by an ejected object.

4, the old refers to the death of the emperor.

Second, etymological explanation.

The pictophonetic word mountain expresses meaning, indicating that the mountain collapsed; A friend's voice is like a series of shells, indicating that the mountain collapsed and the earth and stone rolled down one after another. The original meaning is the collapse of the mountain. Generally refers to collapse.

Third, word formation

Cliff collapse, collapse, collapse, crack, collapse, etc.

Four. Evolution of glyphs (as shown)

Extended data:

First, the cliff collapsed? [yábīng]？

Rock cliffs and mud cliffs suddenly crack and fall off under the action of gravity due to natural weathering and rain erosion.

Second, collapse? [bīng kui]？

Complete destruction; Collapse, esp in national politics, economy, military affairs, etc. ).

Third, collapse? 【bēng tā】？

Split and collapse.

Fourth, division? [ bēng liè ]？

(an object) suddenly splits into several parts.

5. collapse? [ bēng pán ]？

Refers to the complete collapse of stocks, futures and other markets due to a sharp drop in the market.